单词：now and again
时而
now and again的用法和样例：
例句
- He fluctuated between hope and despair.他时而充满希望时而失望。
- Her moods kept changing,now happy, now sad.她的情绪总是变幻不定，时而欢喜，时而忧伤。
- He looked at the girl and smiled.他看着那个姑娘并不时地朝她微笑。
- Bulges and tentacles of ore extend haphazardly from a central mass.矿石的凸出物及细枝不时地从中心块体伸出。